function runAsync1()
{
    var p = new Promise(function(resolve, reject){
        //做一些异步操作
        setTimeout(function(){
            console.log('异步任务1执行完成');
            resolve('随便什么数据1');
        }, 1000);
    });
    return p;            
}

function runAsync2()
{
    var p = new Promise(function(resolve, reject){
        //做一些异步操作
        setTimeout(function(){
            console.log('异步任务2执行完成');
            resolve('随便什么数据2');
        }, 2000);
    });
    return p;            
}

function runAsync3()
{
    var p = new Promise(function(resolve, reject){
        //做一些异步操作
        setTimeout(function(){
            console.log('异步任务3执行完成');
            resolve('随便什么数据3');
        }, 2000);
    });
    return p;            
}

runAsync1()
	.then(function(data){
	    console.log(data);
	    return runAsync2();
	})
	.then(function(data){
		console.log(data);
		return runAsync3();
	})
	.then(function(data){
		console.log(data);
	});